var expect = require("chai").expect;
require("chai").should();

describe('numToText converts numbers to text', () => {
  describe('units', () => {
    [
      { input: 0, actual: 'zero' },
      { input: 1, actual: 'one' },
      { input: 2, actual: 'two' },
      { input: 3, actual: 'three' },
      { input: 4, actual: 'four' },
      { input: 5, actual: 'five' },
      { input: 6, actual: 'six' },
      { input: 7, actual: 'seven' },
      { input: 8, actual: 'eight' },
      { input: 9, actual: 'nine' }
    ].forEach(({ input, actual }) => {
      it(`should convert ${input} to ${actual}`, () => {
        expect(numToText(input)).to.equal(actual)
      })
    })
  })

  describe('tens', () => {
    describe('teens', () => {
      [
        { input: 10, actual: 'ten' },
        { input: 11, actual: 'eleven' },
        { input: 12, actual: 'twelve' },
        { input: 13, actual: 'thirteen' },
        { input: 14, actual: 'fourteen' },
        { input: 15, actual: 'fifteen' },
        { input: 16, actual: 'sixteen' },
        { input: 17, actual: 'seventeen' },
        { input: 18, actual: 'eighteen' },
        { input: 19, actual: 'nineteen' }
      ].forEach(({ input, actual }) => {
        it(`should convert ${input} to ${actual}`, () => {
          expect(numToText(input)).to.equal(actual)
        })
      })
    })
    describe('just the tens', () => {
      [
        { input: 20, actual: 'twenty' },
        { input: 30, actual: 'thirty' },
        { input: 40, actual: 'fourty' },
        { input: 50, actual: 'fifty' },
        { input: 60, actual: 'sixty' },
        { input: 70, actual: 'seventy' },
        { input: 80, actual: 'eighty' },
        { input: 90, actual: 'ninety' }
      ].forEach(({ input, actual }) => {
        it(`should convert ${input} to ${actual}`, () => {
          expect(numToText(input)).to.equal(actual)
        })
      })
    })

    describe('tens and units', () => {
      it('should return twenty one when passed 21', () => {
        expect(numToText(21)).to.equal('twenty one')
      })

      it('should return ninety nine when passed 99', () => {
        expect(numToText(99)).to.equal('ninety nine')
      })
    })
  })

  describe('hundreds', () => {
    describe('just hundreds', () => {
      it('should return one hundred when passed 100', () => {
        expect(numToText(100)).to.equal('one hundred')
      })

      it('should return two hundred when passed 200', () => {
        expect(numToText(200)).to.equal('two hundred')
      })
    })

    describe('any three digit number', () => {
      it('should return one hundred twenty three given 123', () => {
        expect(numToText(123)).to.equal('one hundred and twenty three')
      })
      it('should return five hundred twelve given 512', () => {
        expect(numToText(512)).to.equal('five hundred and twelve')
      })
      it('should return seven hundred one given 701', () => {
        expect(numToText(701)).to.equal('seven hundred and one')
      })
    })
  })

  describe('thousands', () => {
    it('should return seven thousand, two hundred nineteen given 7219', () => {
      expect(numToText(7219)).to.equal('seven thousand, two hundred and nineteen')
    })

    it('should return three hundred and four thousand, two hundred twenty one given 304221', () => {
      expect(numToText(304221)).to.equal('three hundred and four thousand, two hundred and twenty one')
    })
  })

  describe('very large numbers', () => {
    [
      { input: 1000000, output: 'one million' },
      { input: 452000000001, output: 'four hundred and fifty two billion, and one' },
      { input: 452000000012, output: 'four hundred and fifty two billion, and twelve' },
      { input: 452000000120, output: 'four hundred and fifty two billion, one hundred and twenty' },
      { input: 452000000102, output: 'four hundred and fifty two billion, one hundred and two' },
      { input: 100000000100, output: 'one hundred billion, one hundred' },
      { input: Math.pow(10, 12), output: 'one trillion' },
      { input: Math.pow(10, 15), output: 'one quadrillion' },
      { input: 9007199254740991, output: 'nine quadrillion, seven trillion, one hundred and ninety nine billion, two hundred and fifty four million, seven hundred and fourty thousand, nine hundred and ninety one' },
      { input: Number.MAX_SAFE_INTEGER, output: 'nine quadrillion, seven trillion, one hundred and ninety nine billion, two hundred and fifty four million, seven hundred and fourty thousand, nine hundred and ninety one' }
    ].forEach(({ input, output }) => {
      it(`should convert ${input} to ${output}`, () => {
        expect(numToText(input)).to.equal(output)
      })
    })
  })
  
    describe('very very large numbers', () => {
    [
      { input: 9007199254740992, output: 'nine quadrillion' },
      { input: Number.MAX_SAFE_INTEGER + 1, output: 'nine quadrillion' },
      { input: 9507199254740992, output: 'ten quadrillion' },
      { input: 95071992547409920, output: 'ninety five quadrillion' },
      { input: Math.pow(10, 18), output: 'one quintillion' },
      { input: 317.5 * Math.pow(10, 36), output: 'three hundred and eighteen undecillion' }
    ].forEach(({ input, output }) => {
      it(`should convert ${input} to ${output}`, () => {
        expect(numToText(input)).to.equal(output)
      })
    })
  })

  describe('negatives', () => {
    it('should do negative numbers', () => {
      expect(numToText(-1)).to.equal('minus one')
    })
  })
})